Funds are requested to purchase a Phillips 410 electron microscope (EM) to equip our campus with an instrument capable of meeting the greatly increased interest and sophistication in ultrastructural research in several departments. The proposed microscope offers new capabilities not available on our only existing EM, a JEOL model purchased in 1969. The new instrument would be used by experienced microscopists working on federally-funded research projects, thus releasing the older EM for less demanding research and instructional needs. The EM facility was expanded and refurbished in 1982 to accomodate a new instrument and to provide increased space for tissue preparation and sectioning. The facility is overseen by an interdepartmental advisory committee and supervised on a daily basis by an experienced staff technician. At least 12 labs of biology, chemistry and physics faculty do electron microscopial research. Five consider EM a major focus and average 3 users/lab. Electron microscope usage has increased 60% since 1979 and will increase further in 1983-84. Our 13 year old instrument is simply inadequate to meet both time and technical requirements. Major research projects are: structure/function studies of identified neurons and their target cells; ultrastructure and immunocytochemistry of peptidergic retinal neurons; role of tubulin in prokaryotes; development of chick retina; relationship between steroid production and germ cell development; ultrastructure of membranes related to biophysical properties; effects of vasoactive agents on microvascular endothelium structure; internalization and fate of insulin receptors; role of membrane proteins in control of cell growth; and comparative structure and function of testicular and placental tissue in vertebrates.